The present invention relates to projectiles of the type which are fired from an electromagnetic projectile acceleration device provided with parallel acceleration rails for forming a plasma arc cushion.
In principle, electromagnetic projectile acceleration devices are composed of an acceleration member which, in the simplest case, is constituted by two parallel acceleration rails normally disposed in a tube. These rails are traversed by current and simultaneously take over the lateral guidance of the projectile. When a current is switched on, the current flows along the one rail, through an armature arranged to move between the two rails, and then back through the other rail. The magnetic fields thus generated between the rails, while current is flowing through the armature, generate a Lorenz force which propels the armature and the projectile connected or associated with the armature toward the outside.
In principle, the armature may be composed of a solid material. However, the necessary brush contacts between the armature and the rails do not permit velocities of more than about 1000 m/sec. For some time, a change has therefore been made to the use of a plasma arc cushion as the armature.
Such a plasma arc cushion can be, for example, produced by a thin metal foil which, when traversed by a high intensity current, evaporates to form an electrically conductive plasma cloud. Corresponding electromagnetic projectile acceleration devices are disclosed, for example, in DE-OS 3,325,868 and in DE-OS 3,344,636, corresponding to U.S. Pat. No. 4,555,972, issued Dec. 3rd, 1985.
A particular drawback of the prior art devices is the fact that the force to accelerate the projectile is transmitted only through the bottom or rear of the projectile. Therefore, the projectile must be made correspondingly stable, similarly to conventional projectiles accelerated by a propellant charge.